Process of making 2-7 dinitro-anthraquinone



Patented Mar. 22, 1927.

UNITED STATES 1,e22,1es PATENT oFFIcE.

,BEn'rHoLn STEIN, or ELBEBFELD, GERMANY, ASSIGNOR 'ro onissnnm nms'rmCORPORATION, OF NEW YORK, N. Y., A CORPORATION ornnmwm.

PROCESS OF MAKING 2-7 DINITRO-ANTHRAQUINONE.

No Drawing. Application filed June 28, 1926, Serial No. 119,199, and inGermany June 25, 1928.

- known, though it is su posed they are in 30 beta position. This is inicated in the above formulas by attaching the nitrogroups to the centerof the nuclei.

.The enolization of the tetra-nitro-dianthrone is achieved by treatmentwith a weak 35 basic agent such as pyridinefaniline, weak aqueousalcoholic caustic, etc. The oxidation can be achieved by means ofconcentrated nitric acid, chromic acid dissolved in glacial acetic acidor other strongly acting 40 oxidizing agents. The 2-7 dinitro;anthramy00- ending application Serial No. 119,198 fi ed une 28, 1926, isobtainedas end'prodnot of the reaction. My preferred series of reactionsleading from the tetra-'nitro-dianthrone. to the 2-7dinitro-anthraquinone is firstth'e enolization of thetetra-nitro-dianthrone to the tetra-nitro-dianthranol, which byOxidation goes over into tetra-nitro-dianthraquinone and by furtheroxidation, tothe 27 dinitro-anthraquinone. These reactions can best berepresented by the following reaction scheme:

The correct positions of the nitrogrou s in the dianthranol nuclei arenot-perfect y quinone is obtained directly in a high state of puritymelting at least at 284 C. y The following example-will furtherillustrate my invention:

Ewample.10 parts are boiled upin 100 parts f'ip'yridine. The greensolution obtained at rst.turns*soon-. olive-brown and separates lon'gnee dle s with a etallic'lustres The reaction. is diluted with waterand. the, tetragnitrO-diam-ISO thranol pre pitated with acid in" formofbrownish-re crystals; These are filtered 2 tetra-'nitro-dianthrone 45benzol are added and the reaction mass heated to 80 C. until no morefumes of nitrous at a tem' erature of 20/25 G. into 75 partsstrongnitric acid. 'Intense green solution is obtained at first and followingquicklychanges to yellow. To this, 25 parts nitroacid are evolved. Oncooling the 2-7 dinitroanthraquinone separates as beautiful yellowneedles melting at 284/285 G. V I claim: 1. In processes of making 2-7dinit'ro-anthraquinone the step comprising oxidizingtetra-nitro-dianthrone.

2. In processes of making 2-7 dinitro-anthraquinone the ste comprisingenolization of the tetra-nitro-dianthrone to tetra-nitrodianthranol andoxidizing the latter.

3. In processes of making 2-7 dinitro-am thraquinone the stepscomprising treating teti'a-nitrodianthrone with pyridine and treatingthe pyridine salts of the tetra-nitrodianthranol obtained with acid toform the tetra-nitro-dianthranol and oxidizing the 25 latter withconcentrated nitric acid.

my hand.

BERTHOLD STEIN.

